1. Field of the Invention
This invention relates in general to an electronic musical instrument, and relates in particular to an electronic musical instrument which is capable of producing a diminuendo effect of a musical tone similar to an acoustic musical instrument.
2. Technical Background of the Invention
In general, the generation of a musical tone in the keyboard type of electronic musical instruments is controlled through the control of the characteristics of the tone envelopes, by dividing a tone generation process into four regions or states: attack, decay, sustain and release states.
Therefore, when a key-release event is detected in conventional electronic instruments, and a key-off processing is ready to be initiated, the decay processing begins from the envelope level at the time when a key-off event has been detected, in accordance with the diminuendo envelope characteristics provided in the key-release processing.
Also, in the conventional tone synthesizing apparatus, the detailed processing steps for envelope waveform generation are carried out independently of those for the central processing control apparatus.
On the other hand, in an acoustic piano which is an acoustic musical instrument, damper pedals and sustaining pedals are used to achieve long lasting sound effects by pressing on the pedals to release the dampers pressing down the strings. Further, pressing on the pedals is effective even after the key-release event, because of the reverberation achieved by the effects of releasing the dampers. Such a technique is a favorite playing style.
In the conventional electronic musical instruments, when a key-off event is detected, the amplitude of an envelope waveform is decreased at a relatively large predetermined rate, and such a rate is maintained even if dampers and other devices are operated subsequently. These musical instruments, therefore, could not produce such reverberation effects as an acoustic musical instruments, and suffered from the serious deficiency in good musical expressions.
To overcome such a deficiency in the conventional electronic musical instruments, a technique is known of operating a damper pedal so as to provide a "resonance effect" to the process of generating a musical tone as disclosed in a U.S. Pat. No. 4,909,121. When a damper pedal is pressed in the instrument, a resonance tone is added to an ordinarily generated tone, thus generating a tone signal which includes the resonance tone. The resonance tone may be produced by passing an ordinary tone signal through a filter. Alternatively, data obtained by recording a tone actually reproduced on an acoustic piano, when a damper pedal is operated, may be stored in a memory and a resonance tone may be generated by reading out the stored date form the memory. The resonance tone signal may be sounded by itself or after mixing with an ordinary tone signal at a suitable mixing ratio.